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Imaging
| Question | Answer |
|---|---|
| QC Test: Test looks at general image quality and for the presence of artifacts | Overall visual assessment TG18-QC test pattern Daily QC |
| QC Test: Looks for a variation in the shape of the displayed image from the original image | Geometric distortion TG18-QC test pattern Monthly or Quarterly |
| QC Test: Evaluates the ambient light contribution to the light reflected by the display monitor | Reflection TG18-AD test pattern Monthly or Quarterly |
| QC Test: Assesses the displayed luminance values versus the input values from the display system | Luminance response TG18-LN01, TG18-LN08, TG18-LN18, and TG18-CT test patterns |
| QC Test: This test evaluates the image for nonuniformity and effects of viewing at different angles | Luminance dependencies TG18-UNL10 (A) and TG18-UNL80 (B) test patterns |
| QC Test: Asesses the system’s ability to display images of different parts of an image with high fidelity | Resolution TG18-QC and TG18-CX test patterns |
| What is the Plate maintenance schedule? | Cleaned and inspected every 3 months or as needed Erased every 48 hours if unused |
| A PACS system consists of? | Acquisition (imaging modalities) Display (viewing and workstations) Storage (archive server) |
| refers to the professionals who operate the equipment and their relationships and interactions (i.e., assigning responsibility, evaluation of care, action to improve care, etc.) | Quality Assurance |
| tests/checks that must be performed at specific intervals to ensure continued safe equipment operation and performance | Quality Control |
| the adjusting of the image by the computer program to present an image of predetermined image brightness | Rescaling |
| histograms of luminance values used as a reference to evaluate the input intensities and assign predetermined grayscale values | LUT |
| What is the primary factor influencing contrast with DR? | LUT |
| “predicts” patient dose. | DQE |
| an expression of the radiation exposure level that is required to produce an optimal image. | DQE |
| What reflects both the dose to the patient and the total volume of tissue being irradiated. | DAP |
| Pixel pitch is measured in? | Microns |
| The____ layer is a thin layer of plastic to protect the phosphor layer. | Protective |
| The _____layer is the heart of the plate and contains the phosphor, which is usually of the barium fluorohalide family and europium activated. | Phosphor |
| The _____layer is a layer that reflects light released during the reading phase toward the photodetector. | reflective |
| The _____layer reduces and conducts away static electricity. | Conductive |
| The____layer may be in some newer plates to absorb stimulating light and reflect emitted light | Color |
| The ____ layer is a sturdy material to give some rigidity to the plate. | Support |
| The____ layer is a soft layer that protects the back of the plate. | Backing |
| A ____phosphor layer is one with a random distribution of phosphor crystals within the active layer and can be used with both CR and DR systems. | Turbid |
| A ____phosphor layer is one with columnar phosphor crystals within the active layer resembling needles standing on end and packed together. | Structured |
| Copper and gold, have a very large number of free electrons, making them good ____ of electricity | Conductors |
| Glass and plastic, on the other hand, have very few free electrons, making them good ______ | Insulators |
| An object may be electrified by? | friction, by contact, or by induction. |
| The amount of resistance in a conductor depends on four things: | Material Length Cross-sectional area Temperature |
| Materials with an abundance of free electrons that allow a relatively free flow of electricity | Conductors |
| Materials made up of atoms with tightly bound electrons that do not conduct electricity well even when attracted by a potential difference | Insulators |
| Materials that will conduct electricity but not as well as conductors and that will insulate but not as well as insulators | Semi-conductors |
| A closed (complete) pathway for electricity is required for electricity to flow | Closed Circuit |
| An open (broken) pathway, such as occurs when a switch is turned off | Open Circuit |
| circuit elements are wired along a single conductor | Series Circuit |
| circuit elements “bridge” or branch across a conductor | Parallel Circuit |
| glass, wood, plastic; not attracted to magnetic fields at all. | Nonmagnetic Fields |
| water, mercury, gold; weakly repelled by magnetic fields. | Diamagnetic Fields |
| platinum, gadolinium, aluminum; weakly attracted to magnetic fields. | Paramagnetic materials |
| iron, cobalt, nickel; strongly attracted to magnetic materials. | Ferromagnetic materials |
| Devices that convert some form of mechanical energy into electrical energy | Generators |
| Consists of the main power switch, circuit breakers, the autotransformer, the timer circuit, and the primary side of the step-up transformer | Primary Circuit |
| Consists of the secondary side of the step-up transformer, the mA meter, a rectifier bank, and the x-ray tube (except for the filaments) | Secondary Circuit |
| Consists of a rheostat, a step-down transformer, and the filaments | Filament Circuit |
| a device usually wired to the autotransformer that automatically adjusts the power supplied to the x-ray machine to 220 volts | Line Compensator |
| protect against short circuits and electric shock | Circuit breakers |
| an adjustable transformer controlled by the kilovolt peak (kVp) selector on the operating console | Autotransformer |
| an on-off switch for the unit connected to the facility’s power supply | Main Power Switch |
| used to increase the voltage from the autotransformer to the kilovoltage necessary for x-ray production | Step-up Transformer |
| located in this section because it is easier to control (turn on and off) a low voltage than a very high one | Timer Circuit (exposure timer) |
| Serves the same role as timer The patient’s body part of interest is the variable in determining when to terminate exposure Uses a device called an ionization chamber | AEC |
| a device placed in the secondary circuit that monitors x-ray tube current | mA meter |
| The rectifier commonly used in today’s x-ray circuit is a | solid-state rectifier |
| One half of the AC cycle flows through the x-ray tube and the other half is suppressed (blocked). Wastes half of the supply of power & requires twice the exposure time Current passed through at 60 pulses per second | Half-Wave Rectification |
| Rectifies the entire wave form & uses 4 rectifiers Negative half-cycle corresponding to the inverse voltage is reversed so that the anode is always positive | Full Wave Rectification |
| Makes use of the entire cycle Exposure time for any given technique is cut in half Current pulses through at 120 pulses per second | Full Wave Rectification |
| a variable resistor controlled by the mA selector on the operating console | Rheostat |
| works in concert with the rheostat; together, they determine the quantity of electrons boiled off of the filament and available for x-ray production | Exposure Timer |
| used in the filament circuit to increase the current by reducing the voltage that is applied to the filament | Step-down transformer |
| Increases Voltage; Decreases Amperage | Step-up transformer |
| Decreases Voltage; Increases Amperage | Step-down Transformer |
| The _____ is controlled by a rheostat to reflect the mA selected on the control console. | quantity |
| The _____ is a variable resistor controlled by the mA selector on the operating console and when the mA station was selected, the appropriate filament was also selected. | rheostat |
| A technique to take advantage of the more than 16,000 shades of gray. Windowing refers to the shade of gray displayed, and leveling refers to where on the scale the window is set. | Window Width and Window Level |
| Allows text to be added to the image to identify areas of interest or add information important for diagnosis. This should NOT be in place of anatomic side markers. | Annotation |
| Allows for the flipping of the image so that it is oriented properly for interpretation | Image Flip |
| Allows for the changing of the image from negative (bone is white) to positive (bone is dark). Some pathologic conditions are better identified this way. | Image Inversion |
| Just as a magnifying glass is used to better see small structures on film-screen, an electronic magnifying glass is available for use on digital images | Magnification |
| Increases the contrast along the edge of a structure through a sophisticated software function. This part must have been sufficiently exposed and have a low signal-to-noise ratio, because noise is also enhanced. | Edge Enhancement |
| A software function to suppress noise. Image noise is considered a high frequency variation in the histogram, and postprocessing adjustment of these high frequencies can reduce noise. | Smoothing |
| A quantitative function of digital imaging that allows for the pixel value of a selected area of interest to be calculated. This value can then help characterize disease. | Region of Interest |
| Software weighted processing function whereby underexposed areas are made darker and overexposed areas are made lighter. The effect is an image that appears to have lower contrast so that dense and lucent structures are better seen within the same image. | Equilization |
| Occurs when a focused grid is placed upside down on the IR, resulting in the grid lines going opposite the angle of divergence of the x-ray beam. This appears radiographically as a significant loss of exposure along the edges of the image. | Upside down grid cutoff |
| Occurs when the x-ray beam is angled across the lead strips. It is the most common type of grid cutoff and can occur from either the tube or grid being angled. | Off level grid cutoff |
| When is off level grid cutoff normally seen, & what type of grids does it normally effect? | Mobile or horizonatal examinations, focused and parallel grids |
| Occurs when the CR of the x-ray beam is not aligned from side to side with the center of a focused grid. Also called lateral decentering, Appears radiographically as an overall loss of exposure to the IR. | Off Center grid cutoff |
| Occurs when using an SID outside of the recommended focal range. Cutoff occurs if the SID is less than or greater than the focal range. Radiographically, both appear the same—that is, as a loss of exposure at the periphery of the image. | Off Focus Grid Cutoff |
| Anode angle and Anode heel effect have an ____ relationship. | Inverse |
| SID and Anode Heel Effect have an ____ relationship | Inverse |
| Field size and Anode Heel Effect have a ____ relationship. | Direct |
| In regards to an Increase in exposure factors, which have NO effect on IR exposure | Patient motion & Focal Spot Size |
| In regards to an Increase in exposure factors, which have NO effect on Contrast? | mAs, patient motion, focal spot size, SID, and misalignment of the beam |
| In regards to an Increase in exposure factors, which have NO effect on Brightness? | mAs, kVp, Filtration, Collimation, patient motion, patient size/thickness, grid ratio, grid use, focal spot size, SID, OID, misalignment of the beam |
| In regards to an Increase in exposure factors, which have NO effect on Spatial Resolution? | mAs, kVp, filtration, collimation, grid ratio, grid use |
| In regards to an Increase in exposure factors, which have NO effect on Size Distortion? | mAs, kVp, filtration, collimation, patient motion, grid ratio, grid use, focal spot size, misalignment of the beam |
| In regards to an Increase in exposure factors, which have NO effect on Shape Distortion | mAs, kVp, Filtration, Collimation, patient motion, patient size/thickness, grid ratio, grid use, focal spot size, SID, OID |
| What affects Receptor expsoure? | mAs, kVp, SID, grids, tube filtration, beam restriction, anode heel effect, patient factors. |
| What affects Spatial Resolution? | OID, SID, Focal Spot Size, motion, patient factors, angle (tube, part, or receptor) |
| What affects Distortion? | OID,SID, patient factors, angle (tube, part, or receptor) |
| What DOES NOT affect receptor exposure? | OID, focal spot size, motion, angle (tube, part or receptor) |
| What DOES NOT affect Spatial Resolution? | mAs, kVp, grids, tube filtration, beam restriction, anode heel effect |
| What DOES NOT affect Distortion? | mAs, kVp, Focal spot size, grids, tube filtration, beam restriction, motion, anode heel effect, |
Created by:
bre092795